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PubMed1994

[The mental reactive characteristics of patients with neurasthenia and hypertension during frustration].

The response to stress was compared for neurotic subjects and initial hypertension patients. The stress was simulated using Rosenzweig frustration method. The neurotic patients responded by profound psychological revision of the stress situation, complicated relationships of the inner reactions and their apparent manifestations. Hypertensive subjects had less profound emotions, their psychological responses were close to those of healthy subjects.

Adolescent↗
PubMed1996

Infants' responses to frustrating situations: continuity and change in reactivity and regulation.

We examined continuity, stability, and change in behaviors reflecting infant reactivity and regulation. Healthy infants were observed in laboratory situations designed to elicit frustration when they were 5 (N = 87) and 10 months of age (N = 82). Behaviors indicative of reactivity included objective ratings of average intensity cry, peak intensity cry, and latency to cry. In addition, durations of orienting, avoidant, and nonnegative communicative behaviors were assessed as measures of regulation at each age. Results showed that several behaviors changed in level over time. In addition, Confirmatory Factor Analysis revealed both structural continuity and discontinuity: Behaviors were organized into 2 similar factors at 5 and 10 months (Reactivity and Regulation), but the relation between reactivity and regulation became increasingly independent over time, such that reactivity and regulation were negatively correlated at 5 months but not at 10 months. Finally, model-fitting revealed cross-dimension but not within-dimension stability (5-month reactivity predicted 10-month regulation).

Female↗
PubMed2007

Layer frustration, polar order and chirality in liquid crystalline phases of silyl-terminated achiral bent-core molecules.

A novel class of bent-core molecules with oligo(siloxane) or carbosilane units at both ends was synthesized and the self-organization of these molecules was investigated by polarizing microscopy, DSC, X-ray scattering, dielectric and electrooptical methods. Depending on the size of the silicon-containing segments, smectic and columnar liquid crystalline phases are formed. Most smectic phases are low birefringent and composed of macroscopic domains of opposite handedness (dark conglomerate phases). The switching process in these smectic phases is surface stabilized ferroelectric and, depending on the conditions, two distinct slow relaxation processes to nonpolar structures were observed. It is proposed that the smectic phases are built up by chiral and polar SmCsPF layer stacks which are separated by anticlinic interfaces. If the size of these layer stacks is sufficiently large a coupling to the substrate surfaces takes place and ferroelectric switching is observed. It is also suggested that the sponge-like layer distortion, occurring in the low birefringent mesophases, is due to an escape from the local polar order within these SmCsPF layer stacks. For compounds with larger silylated units a steric frustration arises, which leads to layer modulation (columnar ribbon phases) and this is associated with a transition from ferroelectric to antiferroelectric switching. All compounds show a switching of the molecules around the long axis which reverses the layer chirality.

Journal Article↗
PubMed1997

Patient datasheets and generic evaluation sheets: tools for improving patient care, patient satisfaction, and chart documentation while decreasing physician frustrations.

A medical record system that utilizes a patient datasheet and pretyped generic patient evaluation sheets is described. When completed, the patient datasheet facilitates quick access to all of the pertinent patient medical information, improves transmission of instructions to the patient, simplifies record-keeping of patient visits, prevents the rewriting of repetitive information (such as a long list of medications and dosages and instructions after each visit), facilitates the tracing of the patient medication history, and improves communication with the patient and with other physicians. The "generic evaluation sheets" have a near-complete medical history and physical examination already typed with areas where information can be easily added or deleted and provides a place for the patient assessment and medical treatment plan. This approach to outpatient medical record-keeping not only results in the ready availability of patient medical information, thus decreasing some of the frustrations of patient care, but also markedly improves patient care documentation while facilitating referral letters and in-hospital patient records.

Communication↗
PubMed2005

Topological frustrations in Mn films on Fe(001).

The high lateral resolution of spin-polarized scanning tunneling microscopy allows new insights into the spin structure of antiferromagnets on the nanometer range. We demonstrate the capability to image a well-defined in-plane component of the sample spin polarization and discuss the spin structure of antiferromagnetic bct Mn in contact with the ferromagnetic Fe(001) substrate. Mn atoms couple ferromagnetically within a Mn atomic plane, while normal to the surface a layer-wise antiferromagnetic order was found. Magnetic frustrations arise in this system at Fe substrate steps at the interface, where topologically induced 180 degrees domain walls are created in the Mn film. A clear widening of the enforced domain walls with increasing Mn thickness was found. The measured widths could be fitted with a linear function and are explained on the basis of a Heisenberg model.

Crystallography↗
PubMed2002

Non-native interactions, effective contact order, and protein folding: a mutational investigation with the energetically frustrated hydrophobic model.

By Monte Carlo simulations, we explored the effect of single mutations on the thermodynamics and kinetics of the folding of a two-dimensional, energetically frustrated, hydrophobic protein model. Phi-Value analysis, corroborated by simulations beginning from given sets of judiciously chosen initial contacts, suggests that the transition state of the model consists of a limited region of the native structure, that is, a folding nucleus. It seems that the most important contacts in the transition state (large and positive Phi) are not the ones with the highest contact order, because in this case the entropic cost of their formation would be too high, but exactly the ones that decrease the entropic cost of difficult contacts, reducing their effective contact order. Mutations of internal monomers involved in high-order contacts were actually the ones resulting in the fastest kinetics (and Phi < 0), indicating they tend to make low order, non-native contacts of low entropic cost that stabilize the unfolded state with respect to the transition state. Folding acceleration by other non-native interactions was also observed and a simple general mechanism is proposed according to which non-native contacts can act indirectly over the folding nucleus, "chelating" out potentially harmful contacts. The polymer graph of our model, which facilitates the visualization of effective contact orders, successfully suggests the relative kinetic importance of different contacts and is reasonably consistent with analogous graphs for the well characterized family of SH3 domains.

Computer Simulation↗
PubMed2003

Long- and short-range interactions in native protein structures are consistent/minimally frustrated in sequence space.

We show that long- and short-range interactions in almost all protein native structures are actually consistent with each other for coarse-grained energy scales; specifically we mean the long-range inter-residue contact energies and the short-range secondary structure energies based on peptide dihedral angles, which are potentials of mean force evaluated from residue distributions observed in protein native structures. This consistency is observed at equilibrium in sequence space rather than in conformational space. Statistical ensembles of sequences are generated by exchanging residues for each of 797 protein native structures with the Metropolis method. It is shown that adding the other category of interaction to either the short- or long-range interactions decreases the means and variances of those energies for essentially all protein native structures, indicating that both interactions consistently work by more-or-less restricting sequence spaces available to one of the interactions. In addition to this consistency, independence by these interaction classes is also indicated by the fact that there are almost no correlations between them when equilibrated using both interactions and significant but small, positive correlations at equilibrium using only one of the interactions. Evidence is provided that protein native sequences can be regarded approximately as samples from the statistical ensembles of sequences with these energy scales and that all proteins have the same effective conformational temperature. Designing protein structures and sequences to be consistent and minimally frustrated among the various interactions is a most effective way to increase protein stability and foldability.

Amino Acid Sequence↗
PubMed1994

Topological "frustration" in multispanning E. coli inner membrane proteins.

The topology of E. coli inner membrane proteins depends primarily on the distribution of positively charged residues in the molecule. We have constructed model proteins with four potential transmembrane stretches and have systematically explored the topological effects of lysines placed in the loops connecting the transmembrane spans. Our results indicate that membrane insertion is locally determined, with individual "helical hairpins" inserting independently of each other. Topologically "frustrated" molecules, where the charge distribution is such that different parts of the molecule would prefer to insert with incompatible orientations, adopt "leave-one-out" topologies in which only 3 of the 4 potential transmembrane stretches span the membrane. These results are relevant for our general understanding of both membrane protein biogenesis and the evolution of multi-spanning membrane proteins.

Amino Acid Sequence↗
PubMed2005

Topological frustration and the folding of interleukin-1 beta.

The cytokine, interleukin-1beta (IL-1beta), adopts a beta-trefoil fold. It is known to be much slower folding than similarly sized proteins, despite having a low contact order. Proteins are sufficiently well designed that their folding is not dominated by local energetic traps. Therefore, protein models that encode only the folded structure and are energetically unfrustrated (Gō-type), can capture the essentials of the folding routes. We investigate the folding thermodynamics of IL-1beta using such a model and molecular dynamics (MD) simulations. We develop an enhanced sampling technique (a modified multicanonical method) to overcome the sampling problem caused by the slow folding. We find that IL-1beta has a broad and high free energy barrier. In addition, the protein fold causes intermediate unfolding and refolding of some native contacts within the protein along the folding trajectory. This "backtracking" occurs around the barrier region. Complex folds like the beta-trefoil fold and functional loops like the beta-bulge of IL-1beta can make some of the configuration space unavailable to the protein and cause topological frustration.

Computer Simulation↗
PubMed2006

Diabetes mellitus due to misfolding of a beta-cell transcription factor: stereospecific frustration of a Schellman motif in HNF-1alpha.

Maturity-onset diabetes of the young (MODY3), a monogenic form of type II diabetes mellitus, results most commonly from mutations in hepatocyte nuclear factor 1alpha (HNF-1alpha). Diabetes-associated mutation G20R perturbs the dimerization domain of HNF-1alpha, an intertwined four-helix bundle. In the wild-type structure G20 participates in a Schellman motif to cap an alpha-helix; its dihedral angles lie in the right side of the Ramachandran plot (alpha(L) region; phi 97 degrees). Substitutions G20R and G20A lead to dimeric molten globules of low stability, suggesting that the impaired function of the diabetes-associated transcription factor is due in large part to a main-chain perturbation rather than to specific features of the Arg side-chain. This hypothesis is supported by the enhanced stability of non-standard analogues containing D-Ala or D-Ser at position 20. The crystal structure of the D-Ala20 analogue, determined to a resolution of 1.4 A, is essentially identical to the wild-type structure in the same crystal form. The mean root-mean-square deviation between equivalent C(alpha) atoms (residues 5-28) is 0.3 A; (phi, psi) angles of D-Ala20 are the same as those of G20 in the wild-type structure. Whereas the side-chain of A20 or R20 would be expected to clash with the preceding carbonyl oxygen (thus accounting for its frustrated energy landscape), the side-chain of D-Ala20 projects into solvent without perturbation of the Schellman motif. Calorimetric studies indicate that the increased stability of the D-Ala20 analogue (DeltaDeltaG(u) 1.5 kcal/mol) is entropic in origin, consistent with a conformational bias toward native-like conformations in the unfolded state. Studies of multiple substitutions at G20 and neighboring positions highlight the essential contributions of a glycine-specific tight turn and adjoining inter-subunit side-chain hydrogen bonds to the stability and architectural specificity of the intertwined dimer. Comparison of L- and D amino acid substitutions thus provides an example of the stereospecific control of an energy landscape by a helix-capping residue.

Amino Acid Motifs↗
PubMed2004

Poverty and violence, frustration and inventiveness: hospital ward life in Bangladesh.

An ethnographic exploration was done in an orthopaedic ward of a government teaching hospital in Bangladesh to understand the nature of hospital culture in the context of Bangladeshi society at large. Life and work in the ward result in a culture that is simultaneously created by its inhabitants and the conditions in which they are situated. The study shows that biomedicine is a product of particular social conditions and that the hospital reflects features of its society. Behind the injuries and broken limbs in the ward are stories of violence, crime, and intolerance occurring in a society where masses of people fight over limited resources. In the ward people interact in an extremely hierarchical manner. The patients, who are mainly from poor economic backgrounds, remain at the bottom of the hierarchy. Doctors and other staff members are often professionally frustrated. Strikes related to hospital staff's various professional demands hamper the regular flow of work in the ward. Family members are engaged in nursing and provide various kinds of support to their hospitalized relatives. Patients give small bribes to ward boys and cleaners to obtain their day-to-day necessities. Patients joke with each other and mock senior doctors. Thus, they neutralize their powerlessness and drive away the monotony of their stay. Doctors develop 'indigenous' solutions to orthopaedic problems. Instead of using high-tech devices, they employ instruments made of bamboo, bricks, and razor blades. This study shows how medical practice takes shape in an understaffed, under-resourced and poorly financed hospital operating in a low-income country.

Anthropology, Cultural↗
PubMed2000

Inadvertent suture through the chest tube: a simple solution to a frustrating problem.

Although an uncommon complication, inadvertent suturing of the chest tube to the chest wall during closure of a thoracotomy, unfortunately can happen. This frustrating situation likely leads to a rethoracotomy and cutting of the suture in order to release the chest tube. In this report, we propose a fast and easy solution to this problem.

Chest Tubes↗
PubMed2003

Azimuthal frustration and bundling in columnar DNA aggregates.

The interaction between two stiff parallel DNA molecules is discussed using linear Debye-Hückel screening theory with and without inclusion of the dielectric discontinuity at the DNA surface, taking into account the helical symmetry of DNA. The pair potential furthermore includes the amount and distribution of counterions adsorbed on the DNA surface. The interaction does not only depend on the interaxial separation of two DNA molecules, but also on their azimuthal orientation. The optimal mutual azimuthal angle is a function of the DNA-DNA interaxial separation, which leads to azimuthal frustrations in an aggregate. On the basis of the pair potential, the positional and orientational order in columnar B-DNA assemblies in solution is investigated. Phase diagrams are calculated using lattice sums supplemented with the entropic contributions of the counterions in solution. A variety of positionally and azimuthally ordered phases and bundling transitions is predicted, which strongly depend on the counterion adsorption patterns.

Binding Sites↗
PubMed1997

Amsel's frustration effect: a pavlovian replication with control for frequency and distribution of rewards.

Amsel's frustration effect refers to a facilitation of behavior immediately after unexpected nonreward. The original experiments were plagued with problems of interpretation, mainly because the critical comparison involved conditions that were not equated in terms of reward frequency and amount. A replication of the original experiment (with a 50% partial reinforcement schedule used to induce response facilitation) is reported here with one important addition: A control group matched in terms of reward parameters, for which the reward was not signaled by a discrete cue. Matching is achieved through the use of a Pavlovian training procedure. The results show facilitation of rats' lever-contact performance after unexpected reward omissions. The control group showed no facilitation. These results provide support for the view that response facilitation is caused by increased arousal after unexpected nonreward.

Animals↗
PubMed2001

Frustrating case presentations in canine theriogenology.

The practice of small animal theriogenology is rewarding, but frustrations exist concerning technologic advances as compared with other species. Reproductive clinicians striving to practice good quality medicine readily identify topics of common concern: causes that are not identified or therapeutics that are not available or applicable. Improved collaboration among theriogenologists specializing in small animal practice is evidenced by growing attendance at national and international scientific meetings, increased scientific publications, and internet communications.

Animals↗
PubMed2003

Observation of symmetry lowering and electron localization in the doublet-states of a spin-frustrated equilateral triangular lattice: Cu3(O2C16H23) x 1.2C6H12.

Cu3(O2C16H23)6.1.2C6H12, containing a Cu36+ core in an equilateral triangle geometry, has been found to be a versatile model system for investigating the spin-frustration phenomenon in a triangular lattice. It affords well-resolved EPR spectra from both of the two possible (Stotal = 1/2 and 3/2) spin states of the Cu36+ core. From 295 to 100 K, the spectra consist of a triplet, but with the central line overlapped by an additional, sharp peak, which replaces the triplet at 30 K and below. The triplet was thus assigned to the excited state with Stotal = 3/2, located at 324 +/- 5 K ( approximately 225 cm-1), with the zero-field parameters D = -535 G, E = 0, g parallel = 2.209 and g perpendicular = 2.057. The singlet was attributed to the Stotal = 1/2 state, with gxx = 2.005, gyy = 2.050, gzz = 2.282, and, surprisingly, a hyperfine splitting arising from a single Cu2+ nucleus, with Azz = 157 G. The detailed magnetic measurements on a three-electron, equilateral triangular system, and the observation of symmetry lowering in the doublet ground state, should be of broad theoretical and experimental interest in molecular magnetism.

Journal Article↗
PubMed2005

Frustrated molecular packing in highly ordered smectic phase of side-chain liquid crystalline polymer with rigid polyacetylene backbone.

Using poly(5-{[(4'-heptoxy-4-biphenylyl)carbonyl]oxy}-1-pentyne) as an example, we demonstrate the incorporative accommodation of the rigid polyacetylene backbones and the mesogenic pendants, which leads to a highly ordered smectic (Sm) phase with a frustrated structure. The polymer exhibits a recognizable sheetlike molecular shape due to its rigid backbone and relatively short spacer (three methylene units), and the building block of the liquid crystalline (LC) phase is the whole molecule. In the LC phase, five layers of the molecules stack as a smectic A (SmA) block, and adjacent SmA blocks glide halfway of the molecular width from one to another. In scanning tunneling microscopy (STM) experiments, the STM tip scrape is found to generate a regular nanopattern with periodic electron conductivity, of which the spacing is determined by the side-chain length.

Journal Article↗
PubMed2006

Crystal structure and magnetic properties of FeTe2O5X (X=Cl, Br): a frustrated spin cluster compound with a new Te(IV) coordination polyhedron.

A new layered transition metal oxohalide, FeTe2O5ClxBr1-x, has been identified. It crystallizes in the monoclinic space group P21/c. The unit cell for FeTe2O5Br is a = 13.3964(8), b = 6.5966(4), c = 14.2897(6) A, beta=108.118(6) degrees, and Z=8. The layers are built of edge sharing [FeO6] octahedra forming [Fe4O16]20- units that are linked by [Te4O10X2]6- groups. The layers have no net charge and are only weakly connected via van der Waals forces to adjacent layers. There are four crystallographically different Te atoms, and one of them displays a unique [TeO2X] coordination polyhedron (X=Cl, Br). Magnetic susceptibility measurements show a broad maximum typical for 4-spin clusters of coupled Fe(III) ions in the high-spin state. Evidence for magnetic instabilities exists at low temperatures, which have been confirmed with specific heat experiments. A theoretical modeling of the susceptibility concludes a frustration of the intra-tetramer anti-ferromagnetic exchange interaction.

Journal Article↗